Promising prospects for transition metal(Ti, Ni, Zr, and Nb) modified V2C MXene on hydrogen storage performances of magnesium hydride

The mechanism of V2C modified with transition metals (Ti, Ni, Zr, and Nb) on MgH2 dehydrogenation properties were researched by the density functional theory (DFT). The adsorption energy, dehydrogenation energy, and electronic structure of MgH2 on the TM (Ti, Ni, Zr, and Nb) @V2C were calculated. The results showed TM atoms tended to occupy on the fcc site of V2C. The MgH2 adsorption on the V2C were improved by adding TM, the order of the adsorption energy was as follows: Ni@V2C > Ti@V2C > Zr@V2C > Nb@V2C > V2C. The electronic structure indicated an evident orbital hybridization peak between the H and TM atoms. In addition, compared with (MgH2)4 clusters on the V2C, the dehydrogenation energies of that on the TM@V2C were dramatically promoted, with the order of improvement being Ni@V2C > Ti@V2C > Nb@V2C > Zr@V2C. The dehydrogenation energy of (MgH2)4 clusters on the Ni@V2C decreased by 1.60 and 1.11 eV than that pure (MgH2)4 clusters and (MgH2)4 clusters on the V2C, respectively. Therefore, compared with the clean V2C, the influence of the TM@V2C combinations on the dehydrogenation of MgH2 had been extended, providing theoretical support for potential excellent catalysts in experiments.